package eu.kanade.tachiyomi.extension.util

import android.annotation.SuppressLint
import android.content.Context
import android.content.pm.PackageInfo
import android.content.pm.PackageManager
import android.os.Build
import androidx.core.content.pm.PackageInfoCompat
import dalvik.system.PathClassLoader
import eu.kanade.domain.source.service.SourcePreferences
import eu.kanade.tachiyomi.extension.model.Extension
import eu.kanade.tachiyomi.extension.model.LoadResult
import eu.kanade.tachiyomi.source.CatalogueSource
import eu.kanade.tachiyomi.source.Source
import eu.kanade.tachiyomi.source.SourceFactory
import eu.kanade.tachiyomi.util.lang.Hash
import eu.kanade.tachiyomi.util.system.getApplicationIcon
import eu.kanade.tachiyomi.util.system.logcat
import kotlinx.coroutines.async
import kotlinx.coroutines.runBlocking
import logcat.LogPriority
import uy.kohesive.injekt.injectLazy

/**
 * Class that handles the loading of the extensions installed in the system.
 */
@SuppressLint("PackageManagerGetSignatures")
internal object ExtensionLoader {

    private val preferences: SourcePreferences by injectLazy()
    private val loadNsfwSource by lazy {
        preferences.showNsfwSource().get()
    }

    private const val EXTENSION_FEATURE = "tachiyomi.extension"
    private const val METADATA_SOURCE_CLASS = "tachiyomi.extension.class"
    private const val METADATA_SOURCE_FACTORY = "tachiyomi.extension.factory"
    private const val METADATA_NSFW = "tachiyomi.extension.nsfw"
    private const val METADATA_HAS_README = "tachiyomi.extension.hasReadme"
    private const val METADATA_HAS_CHANGELOG = "tachiyomi.extension.hasChangelog"
    const val LIB_VERSION_MIN = 1.3
    const val LIB_VERSION_MAX = 1.4

    private const val PACKAGE_FLAGS = PackageManager.GET_CONFIGURATIONS or PackageManager.GET_SIGNATURES

    // inorichi's key
    private const val officialSignature = "7ce04da7773d41b489f4693a366c36bcd0a11fc39b547168553c285bd7348e23"

    /**
     * List of the trusted signatures.
     */
    var trustedSignatures = mutableSetOf<String>() + preferences.trustedSignatures().get() + officialSignature

    /**
     * Return a list of all the installed extensions initialized concurrently.
     *
     * @param context The application context.
     */
    fun loadExtensions(context: Context): List<LoadResult> {
        val pkgManager = context.packageManager

        @Suppress("DEPRECATION")
        val installedPkgs = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
            pkgManager.getInstalledPackages(PackageManager.PackageInfoFlags.of(PACKAGE_FLAGS.toLong()))
        } else {
            pkgManager.getInstalledPackages(PACKAGE_FLAGS)
        }

        val extPkgs = installedPkgs.filter { isPackageAnExtension(it) }

        if (extPkgs.isEmpty()) return emptyList()

        // Load each extension concurrently and wait for completion
        return runBlocking {
            val deferred = extPkgs.map {
                async { loadExtension(context, it.packageName, it) }
            }
            deferred.map { it.await() }
        }
    }

    /**
     * Attempts to load an extension from the given package name. It checks if the extension
     * contains the required feature flag before trying to load it.
     */
    fun loadExtensionFromPkgName(context: Context, pkgName: String): LoadResult {
        val pkgInfo = try {
            context.packageManager.getPackageInfo(pkgName, PACKAGE_FLAGS)
        } catch (error: PackageManager.NameNotFoundException) {
            // Unlikely, but the package may have been uninstalled at this point
            logcat(LogPriority.ERROR, error)
            return LoadResult.Error
        }
        if (!isPackageAnExtension(pkgInfo)) {
            logcat(LogPriority.WARN) { "Tried to load a package that wasn't a extension ($pkgName)" }
            return LoadResult.Error
        }
        return loadExtension(context, pkgName, pkgInfo)
    }

    /**
     * Loads an extension given its package name.
     *
     * @param context The application context.
     * @param pkgName The package name of the extension to load.
     * @param pkgInfo The package info of the extension.
     */
    private fun loadExtension(context: Context, pkgName: String, pkgInfo: PackageInfo): LoadResult {
        val pkgManager = context.packageManager

        val appInfo = try {
            pkgManager.getApplicationInfo(pkgName, PackageManager.GET_META_DATA)
        } catch (error: PackageManager.NameNotFoundException) {
            // Unlikely, but the package may have been uninstalled at this point
            logcat(LogPriority.ERROR, error)
            return LoadResult.Error
        }

        val extName = pkgManager.getApplicationLabel(appInfo).toString().substringAfter("Tachiyomi: ")
        val versionName = pkgInfo.versionName
        val versionCode = PackageInfoCompat.getLongVersionCode(pkgInfo)

        if (versionName.isNullOrEmpty()) {
            logcat(LogPriority.WARN) { "Missing versionName for extension $extName" }
            return LoadResult.Error
        }

        // Validate lib version
        val libVersion = versionName.substringBeforeLast('.').toDouble()
        if (libVersion < LIB_VERSION_MIN || libVersion > LIB_VERSION_MAX) {
            logcat(LogPriority.WARN) {
                "Lib version is $libVersion, while only versions " +
                    "$LIB_VERSION_MIN to $LIB_VERSION_MAX are allowed"
            }
            return LoadResult.Error
        }

        val signatureHash = getSignatureHash(pkgInfo)

        if (signatureHash == null) {
            logcat(LogPriority.WARN) { "Package $pkgName isn't signed" }
            return LoadResult.Error
        } else if (signatureHash !in trustedSignatures) {
            val extension = Extension.Untrusted(extName, pkgName, versionName, versionCode, libVersion, signatureHash)
            logcat(LogPriority.WARN) { "Extension $pkgName isn't trusted" }
            return LoadResult.Untrusted(extension)
        }

        val isNsfw = appInfo.metaData.getInt(METADATA_NSFW) == 1
        if (!loadNsfwSource && isNsfw) {
            logcat(LogPriority.WARN) { "NSFW extension $pkgName not allowed" }
            return LoadResult.Error
        }

        val hasReadme = appInfo.metaData.getInt(METADATA_HAS_README, 0) == 1
        val hasChangelog = appInfo.metaData.getInt(METADATA_HAS_CHANGELOG, 0) == 1

        val classLoader = PathClassLoader(appInfo.sourceDir, null, context.classLoader)

        val sources = appInfo.metaData.getString(METADATA_SOURCE_CLASS)!!
            .split(";")
            .map {
                val sourceClass = it.trim()
                if (sourceClass.startsWith(".")) {
                    pkgInfo.packageName + sourceClass
                } else {
                    sourceClass
                }
            }
            .flatMap {
                try {
                    when (val obj = Class.forName(it, false, classLoader).newInstance()) {
                        is Source -> listOf(obj)
                        is SourceFactory -> obj.createSources()
                        else -> throw Exception("Unknown source class type! ${obj.javaClass}")
                    }
                } catch (e: Throwable) {
                    logcat(LogPriority.ERROR, e) { "Extension load error: $extName ($it)" }
                    return LoadResult.Error
                }
            }

        val langs = sources.filterIsInstance<CatalogueSource>()
            .map { it.lang }
            .toSet()
        val lang = when (langs.size) {
            0 -> ""
            1 -> langs.first()
            else -> "all"
        }

        val extension = Extension.Installed(
            name = extName,
            pkgName = pkgName,
            versionName = versionName,
            versionCode = versionCode,
            libVersion = libVersion,
            lang = lang,
            isNsfw = isNsfw,
            hasReadme = hasReadme,
            hasChangelog = hasChangelog,
            sources = sources,
            pkgFactory = appInfo.metaData.getString(METADATA_SOURCE_FACTORY),
            isUnofficial = signatureHash != officialSignature,
            icon = context.getApplicationIcon(pkgName),
        )
        return LoadResult.Success(extension)
    }

    /**
     * Returns true if the given package is an extension.
     *
     * @param pkgInfo The package info of the application.
     */
    private fun isPackageAnExtension(pkgInfo: PackageInfo): Boolean {
        return pkgInfo.reqFeatures.orEmpty().any { it.name == EXTENSION_FEATURE }
    }

    /**
     * Returns the signature hash of the package or null if it's not signed.
     *
     * @param pkgInfo The package info of the application.
     */
    private fun getSignatureHash(pkgInfo: PackageInfo): String? {
        val signatures = pkgInfo.signatures
        return if (signatures != null && signatures.isNotEmpty()) {
            Hash.sha256(signatures.first().toByteArray())
        } else {
            null
        }
    }
}
